Hydraulic control device

ABSTRACT

The disclosure provides a hydraulic control device capable of suppressing an excessive increase in the rotation speed of a second pump and stabilizing the discharge pressure of the second pump. The target rotation speed of the second pump for making a pressure value of a first oil close to an estimated value of a pressure value of a third oil is calculated, and a feedback amount with respect to the target rotation speed is calculated by subtracting the estimated value of the pressure value of the third oil from the pressure value of the first oil detected by a hydraulic sensor. Time regions for performing calculation of the feedback amount include an update region in which the feedback amount with respect to the target rotation speed is updated, and a hold region in which update of the feedback amount with respect to the target rotation speed is temporarily stopped.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serialno. 2019-205047, filed on Nov. 12, 2019. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND Technical Field

The disclosure relates to a hydraulic control device in which a secondpump and a bypass valve are connected in parallel between a first pumpand a hydraulic operation part, and which supplies a first oil from thefirst pump to the hydraulic operation part via the bypass valve, orwhich pressurizes the first oil with the second pump and supplies thepressurized first oil as a second oil to the hydraulic operation part.

Description of Related Art

For example, Patent Document 1 discloses a hydraulic control device of avehicle transmission in which a second pump (electric pump) and a bypassvalve (check valve) operated by the drive of a motor are connected inparallel between a first pump (mechanical pump) and a hydraulicoperation part of the transmission. In this case, when the engine isstarted, first, a first oil is supplied from the first pump to thehydraulic operation part via the bypass valve (first state). After that,the second pump is driven by the drive of the motor, and the first oilsupplied from the first pump is pressurized by the second pump, and thepressurized first oil is supplied as the second oil from the second pumpto the hydraulic operation part (second state). The hydraulic operationpart includes, for example, an oil chamber of pulleys (drive pulley anddriven pulley) of a belt-type continuously variable transmission.

In the hydraulic control device having the above configuration,switching between the first state in which the first oil is supplied tothe hydraulic operation part (continuously variable transmission) andthe second state in which the second oil is supplied is performed byopening and closing the bypass valve. That is, when the discharge amount(flow rate) of the second oil from the second pump exceeds the flow rate(discharge amount of the first oil from the first pump) of the first oilpassing through the bypass valve, the hydraulic pressure (line pressurePH) in the downstream oil passage of the bypass valve becomes higherthan the hydraulic pressure (output pressure P1) in the upstream oilpassage. In this way, the bypass valve is closed, and the supply of thefirst oil from the first pump to the hydraulic operation part via thebypass valve is switched to the supply of the second oil from the secondpump to the hydraulic operation part. As a result, the flow of the firstoil to the oil passage is blocked, and the second oil is pumped to thehydraulic operation part by the second pump. On the other hand, when thedischarge amount of the second pump is reduced due to the stop or thelow rotation state of the second pump, the bypass valve is in the valveopen state, and the first oil is supplied to the hydraulic operationpart.

In the above hydraulic control device, the work load of the first pumpis reduced by driving the second pump in the second state. At that time,the target rotation speed of the second pump is calculated by performinga feedback control using the hydraulic pressure of the oil (dischargepressure of the first pump) detected by the hydraulic sensor provided onthe suction side of the second pump. (Patent Document 2)

However, in this hydraulic control device, it is a characteristic of thesecond pump that the torque of the second pump (which is an electricpump) tends to decrease as the rotation speed increases. Therefore, whenthe rotation speed of the second pump increases too much due to theincrease in the feedback amount in the feedback control, the dischargepressure of the second pump may become unstable. As a result, thehydraulic pressure supplied to the hydraulic operation part may not bestable, and the effect of reducing the fuel consumption of the vehiclemay not be sufficiently obtained.

RELATED ART Patent Document

[Patent Document 1] Japanese Laid-open No. 2015-200369

[Patent Document 2] Japanese Laid-open No. 2019-35426

The disclosure has been made in view of the above-mentioned problems ofthe conventional technology, and the disclosure provides a hydrauliccontrol device capable of suppressing an excessive increase in therotation speed of the second pump due to the feedback control incalculating the target rotation speed of the second pump and stabilizingthe discharge pressure of the second pump.

SUMMARY

In view of the foregoing, a hydraulic control device (10) according tothe disclosure, in which a second pump (30) and a bypass valve (58) thatare driven by a motor (32) are connected in parallel between a firstpump (20) and a hydraulic operation part (56) of a transmission, andwhich is switchable between a first state of supplying a first oil fromthe first pump (20) to the hydraulic operation part (56) via the bypassvalve (58) and a second state of pressurizing with the second pump (30)the first oil supplied from the first pump (20) and supplying thepressurized first oil as a second oil to the hydraulic operation part(56), includes: a hydraulic pressure detection part (26) which detectsan oil pressure (P1) of the first oil on a suction side in the secondpump (30); and a control part (28) which calculates a target rotationspeed (NA) of the second pump (30) in the second state. The control part(28) uses a pressure value (P1) of the first oil detected by thehydraulic pressure detection part (26), an estimated value of a pressurevalue (PH) of oil supplied to the hydraulic operation part (56), and anestimated value of a pressure value (P3) of a third oil supplied fromthe first pump (20) to another hydraulic operation part (114) or alubrication target (108) operating at a lower pressure than thehydraulic operation part (56) in the transmission to calculate thetarget rotation speed (NA) of the second pump (30) for matching thepressure value (P1) of the first oil with the estimated value of thepressure value (P3) of the third oil, and subtracts the estimated valueof the pressure value (P3) of the third oil from the pressure value (P1)of the first oil detected by the hydraulic pressure detection part (26)to calculate a feedback amount with respect to the target rotation speed(NA). Time regions for performing calculation of the feedback amountinclude: an update region in which the feedback amount with respect tothe target rotation speed is updated; and a hold region in which updateof the feedback amount with respect to the target rotation speed istemporarily stopped.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of a hydraulic control deviceaccording to an embodiment of the disclosure.

FIG. 2 is a configuration diagram of the line pressure adjusting valve.

In FIG. 3, (a) is a diagram showing an oil flow in a first state, and(b) is a diagram showing an oil flow in a second state.

FIG. 4 is a block diagram showing a calculating procedure of anestimated value of the line pressure.

FIG. 5 is a block diagram showing a calculating procedure of the targetrotation speed of the second pump.

FIG. 6 is a block diagram showing a processing procedure in a controlunit which performs the feedback control.

FIG. 7 is a timing chart for illustrating changes in each value in theservo state.

FIG. 8 is a graph for illustrating the target rotation speed of thesecond pump.

FIG. 9 is a block diagram showing a calculating procedure of the targetrotation speed of the second pump.

FIG. 10 is a graph for calculating the first rotation speed.

FIG. 11 is a graph for calculating the second rotation speed.

FIG. 12 is a graph for calculating the fourth rotation speed.

FIG. 13 is a timing chart showing changes in the target rotation speedof the second pump in the servo state.

FIG. 14 is a timing chart for illustrating the target rotation speed ofthe second pump in the initial mode.

FIG. 15 is a timing chart showing changes in each value in the feedbackmode.

FIG. 16 is a graph for illustrating determination of matching betweenthe output pressure and the estimated value of the line pressure.

FIG. 17 is a timing chart showing changes in each value in each mode ofthe initial mode, the feedback mode, and the fixed mode.

FIG. 18 is a flowchart showing transition conditions of the initialmode, the feedback mode, and the fixed mode.

DESCRIPTION OF THE EMBODIMENTS

According to the hydraulic control device of the disclosure, in thecalculation of the feedback amount with respect to the target rotationspeed of the second pump, the time regions for performing calculation ofthe feedback amount include the update region in which the feedbackamount of the target rotation speed is updated and the hold region inwhich the update of the feedback amount of the target rotation speed istemporarily stopped; as a result, compared with a case where the updateof the feedback amount is continuously updated without being temporarilystopped, since an excessive increase in the rotation speed of the secondpump, which is an electric pump, can be suppressed, the dischargepressure of the second pump can be stabilized. Therefore, since theoperation of the hydraulic operation part can be stabilized, the effectof reducing the fuel consumption of the vehicle can be obtained morereliably. Further, the calculation of the feedback amount in thedisclosure means that the pressure value of the first oil detected bythe hydraulic pressure detection part and the estimated value of thepressure value of the third oil are compared to calculate a value sothat the two are matched, or can be regarded as matching, by thedifference between them.

Further, in this hydraulic control device (10), switching from theupdate region to the hold region may be performed based on that anactual rotation speed (NB) of the second pump (30) with respect to thetarget rotation speed (NA) of the second pump (30) has become outside apredetermined range (L1). Further, in this case, switching from the holdregion to the update region may be performed based on that the actualrotation speed (NB) of the second pump (30) with respect to the targetrotation speed (NA) of the second pump (30) has changed from beingoutside the predetermined range (L1) to being within the predeterminedrange (L1).

According to this configuration, the update region is switched to thehold region when the actual rotation speed of the second pump withrespect to the target rotation speed of the second pump falls outsidethe predetermined range, whereby the actual rotation speed can beprevented from becoming a value that deviates significantly from thetarget rotation speed, and the accuracy of the actual rotation speedwith respect to the target rotation speed can be improved.

Further, since the hold region is switched to the update region when theactual rotation speed of the second pump with respect to the targetrotation speed of the second pump returns to the predetermined range,the update of the feedback amount is restarted when the actual rotationspeed is close to the target rotation speed, whereby the actual rotationspeed can be transitioned to the final target rotation speed earlier.

Further, in this hydraulic control device (10), the control part (28)may end a feedback control and transition to a control which keeps thetarget rotation speed (NA) constant on a condition that a predeterminedtime has elapsed since a difference between the pressure value (P1) ofthe first oil and the estimated value of the pressure value (P3) of thethird oil becomes less than or equal to a predetermined value and thatthe difference between the pressure value (P1) of the first oil and theestimated value of the pressure value (P3) of the third oil perpredetermined time has become within a predetermined range.

When the feedback control is continued, since the feedback amount iscontinuously updated, the target rotation speed of the second pumpcontinues to increase, and the fuel efficiency of the vehicle maydeteriorate. Then, the degree of deterioration of fuel efficiency islarger compared with a case where the feedback amount is fixed.Therefore, here, when the above condition is satisfied, the feedbackcontrol is ended, and the control is transitioned to the control whichkeeps the target rotation speed constant.

The reference numerals in parentheses above indicate the drawingreference numbers of the corresponding components in the embodimentsdescribed later for reference.

In the hydraulic control device according to the disclosure, anexcessive increase in the rotation speed of the second pump due to thefeedback control in calculating the target rotation speed of the secondpump can be suppressed, and the discharge pressure of the second pumpcan be stabilized.

Hereinafter, embodiments of the disclosure will be described withreference to the accompanying drawings. FIG. 1 is a configurationdiagram of a hydraulic control device according to an embodiment of thedisclosure. A hydraulic control device 10 shown in the figure is appliedto, for example, a vehicle 14 equipped with a transmission 12 which is acontinuously variable transmission (CVT).

The hydraulic control device 10 has a first pump (mechanical pump) 20that is driven by an engine 16 of the vehicle 14 and pumps up anddelivers oil (hydraulic oil) stored in a reservoir 18. An oil passage 22for flowing the oil pumped from the first pump 20 as a first oil isconnected to the output side of the first pump 20. A line pressureadjusting valve (pressure adjusting valve) 24, which is a spool valve,is provided in the middle of the oil passage 22.

In the oil passage 22, an output pressure sensor (P1 sensor) 26 isdisposed on the downstream side of the line pressure adjusting valve 24.The output pressure sensor 26 is a hydraulic sensor which sequentiallydetects the pressure (output pressure of the first pump 20) P1 of thefirst oil flowing through the oil passage 22, and which sequentiallyoutputs a detection signal indicating the detected output pressure P1 toa control unit 28 (to be described later). Further, a second pump 30having a capacity smaller than that of the first pump 20 is connected tothe downstream side of the oil passage 22.

The second pump 30 is an electric pump which is driven by the rotationof a motor 32 provided in the vehicle 14 and which outputs the first oilsupplied through the oil passage 22 as a second oil. In this case, thesecond pump 30 can pressurize the supplied first oil and pump thepressurized first oil as the second oil. The motor 32 rotates under thecontrol of a driver 34. The driver 34 controls the drive of the motor 32based on the control signal supplied from the control unit 28, andsequentially outputs a signal indicating the drive state of the motor 32(for example, the rotation speed Nem of the motor 32 according to therotation speed Nep of the second pump 30) to the control unit 28. Anelectric pump unit 36 is configured by the second pump 30, the motor 32,and the driver 34.

In addition, an ACG (alternating current generator) 40 is connected to acrankshaft 38 of the engine 16. The ACG 40 generates power by rotationof the crankshaft 38 due to the drive of the engine 16. The AC powergenerated by the ACG 40 is rectified by a rectifier 42 and charged intoa battery 44. The battery 44 is provided with a voltage sensor 46 whichdetects a voltage V of the battery 44 and a current sensor 48 whichdetects a current I flowing from the battery 44. The voltage sensor 46sequentially detects the voltage V of the battery 44, and sequentiallyoutputs a detection signal indicating the detected voltage V to thecontrol unit 28. The current sensor 48 sequentially detects the currentI flowing from the battery 44, and sequentially outputs a detectionsignal indicating the detected current I to the control unit 28. Thedriver 34 is driven by the power supply from the battery 44.

An oil passage 50 is connected to the output side of the second pump 30.The oil passage 50 is branched into two oil passages 50 a and 50 b onthe downstream side. One oil passage 50 a is connected to a drivenpulley 56 a, which configures a belt-type continuously variabletransmission mechanism 56 of the transmission 12, via a regulator valve52 a and an oil passage 54 a. The other oil passage 50 b is connected toa drive pulley 56 b, which configures the continuously variabletransmission mechanism 56, via a regulator valve 52 b and an oil passage54 b.

A bypass valve 58 is connected in parallel with the second pump 30between the two oil passages 22 and 50. The bypass valve 58 is a checkvalve provided so as to bypass the second pump 30, and allows the flowof oil (first oil) from the oil passage 22 on the upstream side to theoil passage 50 on the downstream side, while blocking the flow of oil(second oil) from the oil passage 50 on the downstream side to the oilpassage 22 on the upstream side.

Further, the oil passage 54 a is provided with a side pressure sensor 62as a hydraulic sensor for detecting the pressure PDN (the pulleypressure, which is the side pressure of the driven pulley 56 a) of theoil supplied to the driven pulley 56 a.

A CR valve 64 is connected to the downstream side of an oil passage 50 cbranching from the oil passage 50. The upstream side of the CR valve 64is connected to the oil passage 50 c, and the downstream side thereof isconnected to two control valves 68 a and 68 b, a CPC valve 70 and an LCCvalve 72 via an oil passage 66. The CR valve 64 is a pressure reducingvalve which decompresses the oil (second oil) supplied from the oilpassage 50 c, and supplies the decompressed oil to the control valves 68a and 68 b, the CPC valve 70, and the LCC valve 72 via the oil passage66.

Each of the control valves 68 a and 68 b is a normally open typesolenoid valve having a solenoid, and is in a valve closed state whilethe control signal (current signal) is supplied from the control unit 28and the solenoid is energized, and is in a valve open state when thesolenoid is not energized.

One control valve 68 a is a solenoid valve for the driven pulley 56 a,and in the valve open state, the control valve 68 a supplies the oilsupplied from the CR valve 64 via the oil passage 66 to the regulatorvalve 52 a via an oil passage 74 a and also to the line pressureadjusting valve 24 via an oil passage 76 a (see FIG. 2). In FIG. 1, forconvenience, the oil passage 76 a is not shown.

Further, the other control valve 68 b is a solenoid valve for the drivepulley 56 b, and in the valve open state, the control valve 68 bsupplies the oil supplied from the CR valve 64 via the oil passage 66 tothe regulator valve 52 b via an oil passage 74 b and also to the linepressure adjusting valve 24 via an oil passage 76 b (see FIG. 2). Inaddition, the oil passage 76 b is also omitted in FIG. 1 forconvenience.

Therefore, in one regulator valve 52 a, the pressure of the oil suppliedfrom the control valve 68 a via the oil passage 74 a is used as a pilotpressure, and when the line pressure PH of the oil supplied via the oilpassages 50 and 50 a is greater than or equal to the predeterminedpressure, the valve is opened and the oil is supplied to the drivenpulley 56 a via the oil passage 54 a. Further, in the other regulatorvalve 52 b, the pressure of the oil supplied from the control valve 68 bvia the oil passage 74 b is used as a pilot pressure, and when the linepressure PH of the oil supplied via the oil passages 50 and 50 b isgreater than or equal to the predetermined pressure, the valve is in thevalve open state, and the oil is supplied to the drive pulley 56 b viathe oil passage 54 b.

In addition, the control valve 68 a can adjust the pressure of the oiloutput to the oil passages 74 a and 76 a. Further, the control valve 68b can adjust the pressure of the oil output to the oil passages 74 b and76 b.

The upstream side of the CPC valve 70 is connected to the oil passage66, and the downstream side thereof is connected to a manual valve 80via an oil passage 78. The CPC valve 70 is a solenoid valve for aforward clutch 82 a and a reverse brake clutch 82 b. In this case, whilethe control signal is supplied from the control unit 28 and the solenoidis energized, the CPC valve 70 is in the valve open state, and the oilpassages 66 and 78 are communicated with each other, and the oil issupplied to the manual valve 80.

The upstream side of the manual valve 80 is connected to the oil passage78; the downstream side thereof is connected to the forward clutch 82 avia an oil passage 84 a, and is connected to the reverse brake clutch 82b via an oil passage 84 b. The manual valve 80 is a spool valve, andwhen a driver operates a range selector 86 provided near the driver'sseat of the vehicle 14 to select any one of the shift ranges such as P(parking), R (reverse), N (neutral), and D (forward, drive), in themanual valve 80, a spool (not shown) moves for a predetermined amount inthe axial direction according to the selected shift range. In this way,the manual valve 80 enables the vehicle 14 to travel in the forwarddirection by supplying the oil supplied via the oil passage 78 to theforward clutch 82 a via the oil passage 84 a, or enables the vehicle 14to travel in the reverse direction by supplying the oil to the reversebrake clutch 82 b via the oil passage 84 b. A clutch pressure sensor 88for detecting the pressure (clutch pressure) of the oil supplied to theoil passage 84 a is provided in the middle of the oil passage 84 a.

A low-pressure hydraulic operation part to which the first oil issupplied via an oil passage 90 is connected to the oil passage 90 thatbranches from the oil passage 22 via the line pressure adjusting valve24. A TC regulator valve 104 and an oil warmer 106 are connected to thedownstream side of the oil passage 90 as the low-pressure hydraulicoperation part, and a lubrication system 108 of the transmission 12 isconnected as a lubrication target. The TC regulator valve 104 isconnected to the LCC valve 72 via an oil passage 110, and a torqueconverter 114 incorporating a lockup clutch 112 is connected to thedownstream side thereof.

The LCC valve 72 is a solenoid valve for the lockup clutch 112, andwhile the control signal is supplied from the control unit 28 and thesolenoid is energized, the LCC valve 72 is in the valve open state, andthe oil passages 66 and 110 are communicated with each other to supplythe oil to the TC regulator valve 104. The TC regulator valve 104 is aspool valve, and the spool (not shown) operates in the axial directionin response to the pressure of the oil supplied from the LCC valve 72via the oil passage 110, whereby a third oil supplied via the oilpassage 90 is decompressed, and the decompressed third oil is suppliedto the torque converter 114 and the lockup clutch 112.

The oil warmer 106 warms the third oil supplied from the oil passage 90to a predetermined temperature, and supplies the warmed third oil to apulley shaft 56 c, a bearing 56 d, and a belt 56 e that configure thecontinuously variable transmission mechanism 56. Further, thelubrication system 108 is various lubrication targets such as bearingsand gears that configure the transmission 12.

The hydraulic control device 10 further includes an engine rotationspeed sensor 116, an oil temperature sensor 118, a vehicle speed sensor120, an accelerator sensor 122, and the control unit 28. The enginerotation speed sensor 116 sequentially detects the engine rotation speedNew of the engine 16 according to the rotation speed Nmp of the firstpump 20, and sequentially outputs a detection signal indicating thedetected engine rotation speed New (rotation speed Nmp) to the controlunit 28. The oil temperature sensor 118 sequentially detects thetemperature (oil temperature) To of the first oil or the second oil, andsequentially outputs a detection signal indicating the detected oiltemperature To to the control unit 28. The vehicle speed sensor 120sequentially detects the vehicle speed Vs of the vehicle 14, andsequentially outputs a detection signal indicating the detected vehiclespeed Vs to the control unit 28. The accelerator sensor 122 sequentiallydetects the opening degree of an accelerator pedal (not shown) operatedby the driver, and sequentially outputs a detection signal indicatingthe detected opening degree to the control unit 28.

The control unit 28 is a microcomputer such as a CPU which functions asa TCU (transmission control unit) which controls the transmission 12 oran ECU (engine control unit) which controls the engine 16. Then, thecontrol unit 28 executes various controls on the hydraulic controldevice by reading and executing programs stored in a storage unit (notshown).

[Line Pressure Adjusting Valve 24]

FIG. 2 is a configuration diagram of the line pressure adjusting valve24. The line pressure adjusting valve 24 is a spool valve incorporatinga first spool 92 a and a second spool 92 b. The first spool 92 a is arelatively long valve body having a substantially I-shaped crosssection, and is disposed inside the line pressure adjusting valve 24along the axial direction (left-right direction in FIG. 2). The secondspool 92 b is a spool having a substantially Y-shaped cross section,which is shorter than the first spool 92 a, and is disposed inside theline pressure adjusting valve 24 on the right side of the first spool 92a along the axial direction. In this case, a first elastic member 94 ais inserted between the first spool 92 a and the second spool 92 b, andthe first elastic member 94 a urges the first spool 92 a to the leftdirection in FIG. 2. Further, the second spool 92 b is urged toward thefirst spool 92 a side by a second elastic member 94 b disposed on theright side of the second spool 92 b.

The line pressure adjusting valve 24 has first to seventh ports 96 a to96 g. The first port 96 a and the second port 96 b are provided so as toface each other at the central part of the outer peripheral surface ofthe line pressure adjusting valve 24. Further, the first port 96 a andthe second port 96 b are communicated with each other regardless of theposition of the first spool 92 a through a groove and the like (notshown) formed on the inner peripheral surface side of the line pressureadjusting valve 24 around the axial direction, and configures a part ofthe oil passage 22. In this case, the first port 96 a is an inlet portfor the first oil in the line pressure adjusting valve 24, and thesecond port 96 b is an outlet port for the first oil.

Then, with the position of the second port 96 b on the outer peripheralsurface of the line pressure adjusting valve 24 as the center, the thirdport 96 c and the fourth port 96 d are sequentially provided on the leftside of FIG. 2 so as to be separated from the second port 96 b, whilethe fifth to seventh ports 96 e to 96 g are sequentially provided on theright side of FIG. 2 so as to be separated from the second port 96 b.

The third port 96 c is provided adjacent to the left side of the secondport 96 b, and the oil passage 90 is connected to the third port 96 c.The fourth port 96 d is provided at the left end of the line pressureadjusting valve 24, and is connected to the oil passage 50 via an oilpassage 98. The fifth port 96 e is provided adjacent to the right sideof the second port 96 b, and is connected to the oil passage 50 via anoil passage 100. In addition, in FIG. 1, for convenience, the oilpassages 98 and 100 are not shown. The sixth port 96 f is provided onthe right side of the fifth port 96 e and is connected to the oilpassage 76 b. The seventh port 96 g is provided at the right end of theline pressure adjusting valve 24 and is connected to the oil passage 76a.

Therefore, oil (first oil or second oil) having the line pressure PHflowing through the oil passage 50 is supplied to the fourth port 96 dand the fifth port 96 e via the oil passages 98 and 100, respectively.Further, the oil is supplied from the control valve 68 b to the sixthport 96 f via the oil passage 76 b. Moreover, the oil is supplied fromthe control valve 68 a to the seventh port 96 g via the oil passage 76a.

On the outer peripheral surface of the first spool 92 a, by forminggrooves in the parts facing the first port 96 a and the second port 96 baround the axial direction, the part facing the first port 96 a isformed as a recess 102 a, and the part facing the second port 96 b isformed as a recess 102 b. Further, on the outer peripheral surface ofthe first spool 92 a, a recess 102 c adjacent to the recess 102 a and arecess 102 d adjacent to the recess 102 b are formed by forming groovesin the parts facing the third port 96 c around the axial direction.

Further, in the line pressure adjusting valve 24, the pressure (linepressure PH, output pressure P1) of the oil supplied to the fourth port96 d is greater than the pressure of the oil supplied to the sixth port96 f and the seventh port 96 g. However, since the oil contact areas ofthe valves are different, the pressures are balanced, and when the oilwith a pressure higher than the balance point is supplied to the fourthport 96 d, the first spool 92 a moves to the right side in FIG. 2 due tothe line pressure PH against the elastic force of the first elasticmember 94 a and the pressure of the oil supplied to the sixth port 96 f.As a result, the recess 102 c and the first port 96 a communicate witheach other, and the first oil can flow into the oil passage 90 via thefirst port 96 a, the recesses 102 c and 102 d, and the third port 96 c.Further, in the line pressure adjusting valve 24, the pressure of thefirst oil flowing through the oil passage 90 may be less than the outputpressure P1 of the first oil flowing through the second pump 30 and thebypass valve 58 via the oil passage 22. Therefore, in the followingdescription, the first oil flowing through the oil passage 90 may bereferred to as the third oil.

Next, the operation of the hydraulic control device 10 according to theembodiment configured as described above will be described. Here, a casewill be described in which the control unit 28 drives and controls thesecond pump 30 by performing the feedback control on the motor 32 mainlyusing the output pressure P1 of the first pump 20 or the line pressurePH (estimated value) (to be described later).

<Basic Operation of Hydraulic Control Device 10>

Prior to the description of the operation of the feedback control, thebasic operation of the hydraulic control device 10 will be described. Inthis basic operation, the operation of the hydraulic system whichsupplies the oil from the reservoir 18 to the continuously variabletransmission mechanism 56 via the first pump 20 and the like will bedescribed.

First, when the first pump 20 starts driving due to the drive of theengine 16, the first pump 20 pumps up the oil in the reservoir 18 andstarts pumping the pumped-up oil as the first oil. As a result, thefirst oil flows through the oil passage 22 via the first port 96 a andthe second port 96 b. The output pressure sensor 26 sequentially detectsthe pressure (output pressure) P1 of the first oil flowing through theoil passage 22, and outputs a signal indicating the detection result tothe control unit 28. Further, the engine rotation speed sensor 116sequentially detects the engine rotation speed New, and sequentiallyoutputs a signal indicating the detection result to the control unit 28.

In this case, since the motor 32 is not driven, the first oil flowingthrough the oil passage 22 flows to the oil passage 50 via the bypassvalve 58 along the line of the thick line, as schematically shown in (a)of FIG. 3. As a result, the first oil is supplied to the fourth port 96d via the oil passages 50 and 98, and is supplied to the fifth port 96 evia the oil passages 50 and 100, and is also supplied to the CR valve 64via the oil passages 50 and 50 c. The CR valve 64 decompresses thesupplied first oil, and supplies the decompressed first oil to thecontrol valves 68 a and 68 b via the oil passage 66, respectively.

Here, control signals (current values IDN, IDR) are supplied in advancefrom the control unit 28 to the solenoids of the control valves 68 a and68 b, and the control valves 68 a and 68 b are in the valve closedstate. Therefore, when the supply of the control signal to each solenoidis stopped, the control valves 68 a and 68 b are switched from the valveclosed state to the valve open state. As a result, the control valve 68a supplies the oil to the regulator valve 52 a via the oil passage 74 aand also supplies the oil to the seventh port 96 g via the oil passage76 a. Further, the control valve 68 b supplies the oil to the regulatorvalve 52 b via the oil passage 74 b and also supplies the oil to thesixth port 96 f via the oil passage 76 b.

The regulator valve 52 a uses the pressure of the oil supplied via theoil passage 74 a as the pilot pressure, and when the pressure of thefirst oil is greater than or equal to a predetermined pressure, theregulator valve 52 a is in a communication state, and the first oil issupplied to the driven pulley 56 a via the oil passage 54 a. The sidepressure sensor 62 sequentially detects the pressure (pulley pressurePDN, which is also the side pressure) of the first oil supplied to thedriven pulley 56 a, and sequentially outputs a signal indicating thedetection result to the control unit 28.

In addition, the regulator valve 52 b uses the pressure of the oilsupplied via the oil passage 74 b as the pilot pressure, and when thepressure (line pressure PH) of the first oil is greater than or equal toa predetermined pressure, the regulator valve 52 b is in a communicationstate, and the first oil is supplied to the drive pulley 56 b via theoil passage 54 b.

Further, in the line pressure adjusting valve 24, the first oil issupplied to the fourth port 96 d, and the oil is supplied from thecontrol valve 68 b to the sixth port 96 f, while the oil is alsosupplied from the control valve 68 a to the seventh port 96 g. In thiscase, since the pressure (line pressure PH, output pressure P1) of thefirst oil is greater than the pressure of the oil from each of thecontrol valves 68 a and 68 b, the first spool 92 a moves to the rightside in FIG. 2 due to the line pressure PH against the elastic force ofthe first elastic member 94 a and the pressure of the oil. As a result,the recess 102 c and the first port 96 a communicate with each other,and the first oil can be supplied to a low-pressure system such as thelubrication system 108 as the third oil via the first port 96 a, therecesses 102 c and 102 d, the third port 96 c, and the oil passage 90.

In this way, when a control signal is supplied from the control unit 28to the driver 34 in the state where the first pump 20 is being driven,the driver 34 drives the motor 32 based on the control signal and drivesthe second pump 30. As a result, the second pump 30 outputs the firstoil flowing through the oil passage 22 as the second oil.

Then, when the second oil flows through the oil passage 50 and the flowrate of the second oil (discharge flow rate of the second pump 30)exceeds the flow rate of the first oil (discharge flow rate of the firstpump 20), in the bypass valve 58, the pressure (line pressure PH) of theoil on the oil passage 50 side becomes greater than the pressure (outputpressure P1) of the oil on the oil passage 22 side. As a result, thebypass valve 58 is in the valve closed state, and the supply of thefirst oil from the first pump 20 to the continuously variabletransmission mechanism 56 and the like via the bypass valve 58 and theoil passage 50 as shown in (a) of FIG. 3 is switched to the supply ofthe second oil from the second pump 30 to the continuously variabletransmission mechanism 56 and the like via the oil passage 50 as shownby the thick line in (b) of FIG. 3. As a result, the flow of the firstoil to the oil passage 50 is blocked, and the second oil is pumped bythe second pump 30 to the continuously variable transmission mechanism56 and the like. The second oil is supplied to the fourth port 96 d viathe oil passages 50 and 98, is supplied to the fifth port 96 e via theoil passages 50 and 100, and is supplied to the CR valve 64. Further,the driver 34 sequentially outputs a signal indicating the motorrotation speed Nem of the motor 32 (rotation speed Nep of the secondpump 30) to the control unit 28.

The CR valve 64 decompresses the supplied second oil, and supplies thedecompressed second oil to the control valves 68 a and 68 b via the oilpassage 66, respectively. Since the control valve 68 a is in the valveopen state, it supplies the oil to the regulator valve 52 a via the oilpassage 74 a and also supplies the oil to the seventh port 96 g via theoil passage 76 a. Further, since the control valve 68 b is also in thevalve open state, it supplies the oil to the regulator valve 52 b viathe oil passage 74 b and also supplies the oil to the sixth port 96 fvia the oil passage 76 b.

As a result, the regulator valve 52 a supplies the second oil to thedriven pulley 56 a with the pressure of the oil supplied via the oilpassage 74 a as the pilot pressure. The side pressure sensor 62sequentially detects the pressure (side pressure PDN) of the second oilsupplied to the driven pulley 56 a and outputs it to the control unit28. In addition, the regulator valve 52 b supplies the second oil to thedrive pulley 56 b with the pressure of the oil supplied via the oilpassage 74 b as the pilot pressure.

In this way, since the pressurized second oil is supplied to the drivenpulley 56 a and the drive pulley 56 b, the pressure (output pressure) P1of the first oil can be reduced, and the load on the first pump 20 canbe reduced. In this case, the first spool 92 a moves to the right sidein FIG. 2 with the pressure (line pressure PH) of the second oilsupplied to the fourth port 96 d of the line pressure adjusting valve 24as the pilot pressure, and the output pressure P1 can be reduced byincreasing the opening degree (opening area) between the first port 96 aand the recess 102 c.

Further, in the line pressure adjusting valve 24, the oil is supplied tothe sixth port 96 f and the seventh port 96 g, respectively. In thiscase, since the line pressure PH is greater than the pressure of theoil, the first spool 92 a further moves to the right side in FIG. 2against the elastic force of the first elastic member 94 a and thepressure of the oil. As a result, when the recess 102 b and the fifthport 96 e communicate with each other, the oil passage 22 and the oilpassage 100 communicate with each other. As a result, an increase in thepressure (line pressure PH) of the second oil supplied to the oilpassage 100 is suppressed, and the line pressure PH can be maintained ata predetermined pressure.

Here, a state in which the second pump 30 is operated and the second oilis supplied from the second pump 30 will be described in detail. Inaddition, in the following description, the state in which the secondpump 30 is operated and the second oil is supplied from the second pump30 is referred to as a “servo state.”

Here, first, in describing the change of each value in the servo state,the calculation of the target rotation speed NA of the second pump 30 inthe servo state will be described. In the calculation of the targetrotation speed NA of the second pump 30, first, the control unit 28calculates the estimated value of the line pressure PH, and calculatesan estimated value of the pressure P3 of the third oil (hereinafterreferred to as “low hydraulic pressure”).

<Estimation of Line Pressure PH>

FIG. 4 is a block diagram showing a calculating procedure of anestimated value of the line pressure PH. The control unit 28 uses thecurrent value IDN, which is a control signal supplied to the solenoid ofthe control valve 68 a, and the current value IDR, which is a controlsignal supplied to the solenoid of the control valve 68 b, and refers tovarious maps stored in advance to calculate an estimated value of theline pressure PH.

The control unit 28 estimates the line pressure PH (estimated linepressure PH) according to a command value with the side pressure (pulleypressure) PDN or the like as the command value.

The side pressure PDN of the driven pulley 56 a is the pressure of theoil supplied from the oil passage 50 to the driven pulley 56 a via theoil passage 50 a, the regulator valve 52 a and the oil passage 54 a. Theside pressure PDN can be adjusted according to the pressure (pilotpressure) of the oil supplied from the control valve 68 a to theregulator valve 52 a via the oil passage 74 a. Further, the sidepressure PDR of the drive pulley 56 b is the pressure of the oilsupplied from the oil passage 50 to the drive pulley 56 b via the oilpassage 50 b, the regulator valve 52 b and the oil passage 54 b. Theside pressure PDR can be adjusted according to the pressure (pilotpressure) of the oil supplied from the control valve 68 b to theregulator valve 52 b via the oil passage 74 b.

Therefore, the control unit 28 refers to a 3D map stored in advance, andobtains an estimated value of the side pressure PDN (estimated sidepressure PDNe serving as a command value) according to the controlsignal (current value IDN) supplied to the solenoid of the control valve68 a. Further, the control unit 28 refers to a 3D map stored in advance,and obtains an estimated value of the side pressure PDR (estimated sidepressure PDRe serving as a command value) according to the controlsignal (current value IDR) supplied to the solenoid of the control valve68 b.

Each 3D map is a three-dimensional map showing the relationship betweenthe current values IDN and IDR and the estimated side pressures PDNe andPDRe generated for each oil temperature To of the first oil or thesecond oil. Therefore, the control unit 28 specifies the estimated sidepressures PDNe and PDRe according to the current oil temperature To andthe current values IDN and IDR from the 3D maps.

Next, the control unit 28 determines the higher hydraulic pressure valueof the two specified estimated side pressures PDNe and PDRe as a targetside pressure PDm. Next, the control unit 28 refers to a 1D map storedin advance, and specifies a target value PHt of the line pressure PHaccording to the target side pressure PDm. The 1D map is aone-dimensional map showing the relationship between the target sidepressure PDm and the line pressure PH.

Finally, the control unit 28 determines a value obtained by adding apredetermined amount of margin to the target value PHt as an estimatedvalue of the line pressure PH (estimated line pressure PH).

<Estimation of Low Hydraulic Pressure P3>

The control unit 28 refers to multiple maps corresponding to eachcomponent of the hydraulic system of the transmission 12 stored inadvance to estimate the pressure (low hydraulic pressure) P3 of thethird oil supplied to the TC regulator valve 104, the oil warmer 106,and the lubrication system 108 via the oil passage 90.

The characteristics of each component configuring the hydraulic systemof the transmission 12 are stored in advance as a map. Therefore, thecontrol unit 28 estimates the low hydraulic pressure P3 (estimated valueP3 e) by using the map of the characteristics of each component storedin advance.

Specifically, the control unit 28 estimates the pressure PCR of the oilpassing through the CR valve 64 by using the estimated value of the linepressure PH and the current value ICPC of the control signal supplied tothe CPC valve 70. In this case, the control unit 28 obtains the pressurePCR for each temperature and sets the obtained characteristics of thepressure PCR as a map.

Next, the control unit 28 estimates the pressure PLCC of the oil passingthrough the TC regulator valve 104 by using the map of the pressure PCRand the current value ILCC of the control signal supplied to thesolenoid of the LCC valve 72. The pressure PLCC is also the pressure ofthe oil supplied to the lockup clutch 112. In this case, the controlunit 28 obtains the pressure PLCC for each temperature and sets theobtained characteristics of the pressure PLCC as a map.

Next, the control unit 28 obtains the leakage amount of the hydraulicpath leading to the driven pulley 56 a and the drive pulley 56 b via theoil passages 50, 50 a and 50 b from the maps of the current values IDNand IDR and the side pressures PDN and PDR. Further, the control unit 28obtains the leakage amount of the LCC valve 72 from the map of thecurrent value ILCC, and obtains the leakage amount of the CR valve 64and the leakage amount of the CPC valve 70 from the map of the currentvalue ICPC.

Further, the control unit 28 calculates the flow rate (shift flow rateof the driven pulley 56 a and the drive pulley 56 b) of the second oilto be supplied to the continuously variable transmission mechanism 56during the shift operation from the area of the pulley chamber of thedriven pulley 56 a and the drive pulley 56 b and the rotation speed ofthe driven pulley 56 a and the drive pulley 56 b.

Then, the control unit 28 calculates the flow rate QPH of the oil to besupplied to the high-pressure hydraulic system from the second pump 30to the driven pulley 56 a and the drive pulley 56 b by adding theleakage amount in the hydraulic path leading to the driven pulley 56 aand drive pulley 56 b, the leakage amount of the LCC valve 72, theleakage amount of the CPC valve 70, the leakage amount of the CR valve64, the shift flow rate, and the leakage amount of the driven pulley 56a and the drive pulley 56 b.

Next, the control unit 28 calculates the flow rate Q3 of the third oilsupplied to the low-pressure system via the oil passage 90 bysubtracting the flow rate QPH from the discharge flow rate of the firstoil from the first pump 20.

Next, the control unit 28 calculates an estimated value of the lowhydraulic pressure P3 according to the oil temperature To of the firstoil or the second oil based on the pressure PLCC of the oil passingthrough the TC regulator valve 104 and the flow rate Q3 of the thirdoil.

FIG. 5 is a block diagram showing a calculating procedure of the targetrotation speed NA of the second pump 30. In the calculation of thetarget rotation speed of the second pump 30, as shown in FIG. 5, arequired flow rate calculation part 153 calculates an oil flow rate(required flow rate) 154 required for the continuously variabletransmission mechanism 56, which is a hydraulic operation part, by usingan estimated value 151 of the line pressure PH and an oil temperature152 detected by the oil temperature sensor 118. Further, a differentialpressure calculation part 157 obtains an estimated value 158 of thedifferential pressure ΔP (=line pressure PH−low hydraulic pressure P3)by using an estimated value 155 of the line pressure PH and an estimatedvalue 156 of the low hydraulic pressure P3. Further, an F/B amountcalculation part 162 calculates a feedback amount 163 by using adetected value 159 of the output pressure P1 detected by the outputpressure sensor 26 and an estimated value 160 of the low hydraulicpressure P3. Then, an addition part 164 calculates an addition value 165by adding the feedback amount 163 to the calculated value 158 of thedifferential pressure ΔP, and a rotation speed calculation part 166calculates the target rotation speed NA of the second pump 30 by usingthis addition value 165 and the required flow rate 154.

The calculation of the feedback amount by the F/B amount calculationpart 162 will be described in detail. FIG. 6 is an illustrating diagramshowing processing in the control unit 28 which performs the feedbackcontrol with respect to the differential pressure ΔP by using the outputpressure P1 detected by the output pressure sensor 26. That is, FIG. 6is a control method for feedback-controlling the output pressure P1 withthe estimated value of the low hydraulic pressure P3 as the target valueby feeding back to the control unit 28 the change amount of the outputpressure P1 as the rotation speed of the second pump 30 increases.

When the estimated value of the line pressure PH is estimated and theestimated value of the low hydraulic pressure P3 is estimated, thecontrol unit 28 generates a command value ΔPi (=PHe−P3 e) of thedifferential pressure ΔP by subtracting the estimated value of the lowhydraulic pressure P3 from the estimated value of the line pressure PH.Further, the control unit 28 calculates an estimated value ΔPe (=PHe−P1)of the differential pressure ΔP by subtracting the output pressure P1detected by the output pressure sensor 26 from the estimated value ofthe line pressure PH.

Next, the control unit 28 obtains a deviation Ae (=ΔPi−ΔPe) bysubtracting the estimated value ΔPe from the command value ΔPi. Theobtained deviation Ae is passed through a proportional integrationelement (PI control) and added to the command value ΔPi. That is, thecontrol unit 28 performs the feedback control with the deviation Ae asthe feedback amount for the command value ΔPi.

In this case, Ae=ΔPi−ΔPe=(PHe−P3 e)−(PHe−P1)=P1−P3 e. Therefore, thecontrol unit 28 performs the feedback control for the command value ΔPiso that the output pressure P1 becomes an estimated value of the lowhydraulic pressure P3. Next, the control unit 28 adjusts the commandvalue ΔPi after the feedback control in consideration of the oiltemperature To of the first oil or the second oil as well. After that,the required flow rate Q and the adjusted command value ΔPi are used tocalculate the command value of the rotation speed for the second pump30.

FIG. 7 is a timing chart for illustrating changes in each value in theservo state. This timing chart shows the changes of the output pressureP1, the line pressure PH (estimated value), the low hydraulic pressureP3 (estimated value), the operation state (operational/stopped) and theoperation mode (initial mode, feedback mode, fixed mode) of the secondpump 30, the target rotation speed NA and the actual rotation speed NBof the second pump 30 with respect to the elapsed time t.

In the timing chart of FIG. 7, the second pump 30 is stopped before thetime point t11. In this state, the first oil is supplied from the firstpump 20 to the continuously variable transmission mechanism 56 via thebypass valve 58 and the oil passage 50 (see (a) of FIG. 3). Therefore,the output pressure P1 which is the pressure of the first oil flowingthrough the oil passage 50 is equal to the line pressure PH (outputpressure P1=line pressure PH). Further, the low hydraulic pressure P3 isless than the line pressure PH and the output pressure P1 (line pressurePH>low hydraulic pressure P3, output pressure P1>low hydraulic pressureP3).

Then, when the second pump 30 operates at the time point t11, it is thenswitched to the supply of the second oil from the second pump 30 to thecontinuously variable transmission mechanism 56 via the oil passage 50(see (b) of FIG. 3). Therefore, after the state shown in (b) of FIG. 3is reached, the pressure of the second oil becomes the line pressure PH.

Here, the control unit 28 of the hydraulic control device 10 controlsthe motor 32 via the driver 34 so that the actual rotation speed NB ofthe second pump 30 (torque of the second pump 30) increases with respectto the elapsed time t. Accordingly, the flow rate of the second oildischarged from the second pump 30 gradually increases as the actualrotation speed NB of the second pump 30 increases. As a result, afterthe time point t11, the output pressure P1 can be gradually reduced withthe elapsed time t.

Then, in the operation state (servo state) of the second pump 30, thesecond pump 30 is operated by sequentially passing through each mode ofthe initial mode (INI mode), the feedback mode (F/B mode) and the fixedmode (FIX mode). In the initial mode, the target rotation speed NA ofthe second pump 30 increases at the time point t11, and the actualrotation speed NB gradually increases following the target rotationspeed NA. Further, in this initial mode, the target rotation speed NA ofthe second pump 30 is a rotation speed that can discharge only the flowrate required for consumption in the hydraulic operation part (targetrotation speed corresponding to only the required flow rate 154 in FIG.5). Therefore, the output pressure P1 does not decrease during theinitial mode. When it is determined that the actual rotation speed NB ofthe second pump 30 matches the target rotation speed NA, the initialmode ends.

In the feedback mode following the initial mode, the output pressure P1gradually decreases toward the low hydraulic pressure P3 as the actualrotation speed NB of the second pump 30 gradually increases. At the sametime, the feedback control of the rotation speed of the second pump 30is performed. That is, the control unit 28 performs the feedback controlof the rotation speed of the second pump 30 by using the output pressureP1 detected by the output pressure sensor 26, the estimated value of theline pressure PH, and the estimated value of the low hydraulic pressureP3. In this feedback mode, the output pressure P1 is feedback-controlledwith the low hydraulic pressure P3 as the target value by feeding backthe change amount of the output pressure P1 due to the increase in theactual rotation speed NB of the second pump 30 to the control unit 28.

As a result, for example, due to the error between the control value ofeach pressure and the actual pressure value and the variation in thedischarge performance of the second pump 30, even if the output pressureP1 cannot be reduced to the low hydraulic pressure P3 by using thetarget rotation speed of open control (the target rotation speedcorresponding to the calculated value 158 of the differential pressureΔP (=line pressure PH−low hydraulic pressure P3) shown in FIG. 5), inthe feedback mode after the time point t12, the output pressure P1 canbe reduced to the low hydraulic pressure P3 by using the target rotationspeed to which the feedback amount (F/B amount 163 in FIG. 5) is added.

When the feedback mode ends at the time point t13, the output pressureP1 drops to the low hydraulic pressure P3 at this time point (P1≈P3),and then the output pressure P1 is maintained at the low hydraulicpressure P3 (fixed mode). That is, in the fixed mode, the state of P1≈P3is maintained by keeping the rotation speed of the second pump 30substantially constant. After that, when the operation of the secondpump 30 is stopped at the time point t14, the target rotation speed NAof the second pump 30 becomes the stop rotation speed (≈0), and theactual rotation speed NB also decreases following the target rotationspeed NA and gradually becomes the stop rotation speed. As a result,after the time point t14, the output pressure P1 gradually increasestoward the line pressure PH. When the output pressure P1 is reduced bythe operation of the second pump 30 as described above, the work load ofthe first pump 20 is reduced, and the fuel efficiency of the vehicle 14can be expected to be improved.

Here, the target rotation speed of the second pump 30 in the servo statewill be described in detail. In the servo state, as shown in FIG. 5, thetarget rotation speed NA of the second pump 30 is calculated, and thesecond pump 30 is operated based on the target rotation speed NA. Atthis time, the target rotation speed NA of the second pump 30 is set sothat the output pressure P1 matches the estimated value of the lowhydraulic pressure P3. FIG. 8 is a graph for illustrating the targetrotation speed NA of the second pump 30, with the horizontal axisrepresenting the rotation speed of the second pump 30, and the verticalaxis representing the pressure. As shown in the graph in the figure, thefinal target rotation speed NA of the second pump 30 in the second stateis the total value of a first rotation speed N1, a second rotation speedN2, a third rotation speed N3, and a fourth rotation speed N4. The firstrotation speed N1 is a rotation speed required to discharge the oil ofthe flow rate consumed by the continuously variable transmissionmechanism 56 (the total of the shift flow rate and the required flowrate including the leakage flow rate). The second rotation speed N2 is arotation speed required to reduce the output pressure P1 from theestimated value of the line pressure PH to the estimated value of thelow hydraulic pressure P3. The third rotation speed N3 is a rotationspeed corresponding to the feedback (F/B) amount when performing thefeedback correction for correcting the difference (error amount) betweenthe output pressure P1, which has been reduced at the second rotationspeed N2, and the estimated value of the low hydraulic pressure P3. Thefourth rotation speed N4 is a rotation speed as a fixed mode additionterm, which is added to ensure that the output pressure P1 matches theestimated value of the low hydraulic pressure P3 in the fixed mode. Thatis, the final target rotation speed NA of the second pump 30=the firstrotation speed N1+the second rotation speed N2+the third rotation speedN3+the fourth rotation speed N4. Further, here, the difference (erroramount) between the output pressure P1, which has been reduced at thesecond rotation speed N2, and the estimated value of the low hydraulicpressure P3 may be caused because in some cases, there is an error(deviation of the estimated value) in the estimated value of the linepressure PH, and due to the error, even if the output pressure P1 isreduced based on the second rotation speed N2 calculated by using theestimated value of the line pressure PH, it does not completely matchthe estimated value of the low hydraulic pressure P3, and thus there isa difference between the output pressure P1 and the estimated value ofthe low hydraulic pressure P3. Therefore, this difference is correctedby the third rotation speed N3, which is the feedback (F/B) amount.Hereinafter, the calculation method of the first to fourth rotationspeeds N1 to N4 will be described.

FIG. 9 is a block diagram showing a calculating procedure of the targetrotation speed NA of the second pump 30. As shown in the figure, in thecalculation of the target rotation speed NA of the second pump 30,first, a consumption flow rate 204 of the continuously variabletransmission mechanism 56 is calculated by adding an estimated leakageflow rate 201 of the oil passage 50 through which the oil with the linepressure PH flows and a shift flow rate 202 of the continuously variabletransmission mechanism 56 by an addition part 203, and a first rotationspeed calculation part 206 calculates the first rotation speed N1 whichis the rotation speed required to supply the oil of the consumption flowrate (total of the required flow rate and the shift flow rate) of thecontinuously variable transmission mechanism 56 based on the consumptionflow rate 204 and the oil temperature 205.

FIG. 10 is a graph for calculating the first rotation speed N1. In thegraph of the figure, the horizontal axis represents the required flowrate, and the vertical axis represents the rotation speed of the secondpump 30. As shown in the figure, the first rotation speed N1 iscalculated by searching for a value on a map by using the map showingthe relationship between the required flow rate and the rotation speedgenerated for each oil temperature. Here, the required flow rate and therotation speed are in a proportional relationship for each oiltemperature. Therefore, the first rotation speed N1 is determined fromthe required flow rate and the oil temperature.

With reference back to FIG. 9, next, an addition part 210 adds afeedback correction term 211 to a value obtained by subtracting anestimated value 208 of the low hydraulic pressure P3 from an estimatedvalue 207 of the line pressure PH by a subtraction part 209. Based onthis value and an oil temperature 212, a second and third rotation speedcalculation part 213 calculates the total value of the second rotationspeed N2 and the third rotation speed N3, which is the rotation speed ofthe second pump 30 required to reduce the output pressure P1 to theestimated value of the low hydraulic pressure P3.

FIG. 11 is a graph for calculating the rotation speed (second rotationspeed N2) of the second pump 30 required to reduce the output pressureP1 to the estimated value of the low hydraulic pressure P3. In the graphof the figure, the horizontal axis represents the differential pressureΔP=output pressure P1−low hydraulic pressure P3 (estimated value), andthe vertical axis represents the rotation speed of the second pump 30.In the calculation of the second rotation speed N2, the second rotationspeed N2 is calculated by searching for a value on a map by using themap showing the relationship between ΔP=output pressure P1−low hydraulicpressure P3 (estimated value) and the rotation speed generated for eachoil temperature. As shown in the graph of the figure, in a state wherethe second pump 30 supplies the consumption flow rate (required flowrate) of the continuously variable transmission mechanism 56, thedifferential pressure and the flow rate of the second pump 30 are in aproportional relationship for each oil temperature. Therefore, thesecond rotation speed N2, which is the required rotation speed, isdetermined from ΔP=output pressure P1−low hydraulic pressure P3(estimated value) and the oil temperature. Further, the third rotationspeed N3, which is the feedback amount, is a rotation speed calculatedby the procedure shown in FIG. 6.

Further, in the fixed mode, even if the rotation speed of the secondpump 30 is maintained at the minimum rotation speed such that the outputpressure P1 becomes equal to the estimated value of the low hydraulicpressure P3, since the ratio of the continuously variable transmissionmechanism 56 changes from that state, the output pressure P1 may becomea value that does not match the estimated value of the low hydraulicpressure P3. Therefore, in the fixed mode, an addition rotation speedfor the fixed mode (fourth rotation speed N4) is added to the targetrotation speed of the second pump 30 as a control for more accuratelymatching the output pressure P1 with the estimated value of the lowhydraulic pressure P3.

FIG. 12 is a graph for calculating the addition rotation speed (fourthrotation speed N4) for the fixed mode, and the horizontal axisrepresents the ratio (gear ratio) of the continuously variabletransmission mechanism 56, and the vertical axis represents the additionrotation speed (fourth rotation speed N4). As shown in the graph of thefigure, the addition rotation speed for the fixed mode is calculatedbased on a map that defines the relationship between the ratio (gearratio) of the continuously variable transmission mechanism 56 for eachoil temperature and the addition rotation speed. Here, the reason whythe ratio (gear ratio) of the continuously variable transmissionmechanism 56 is required as a parameter is that the shift flow ratediffers even if the change rate of the ratio is the same, and the reasonwhy the oil temperature is required is that the discharge performance ofthe second pump 30 differs depending on the oil temperature.

With reference back to FIG. 9 again, a base value 215 of the targetrotation speed NA of the second pump 30 is calculated by adding by anaddition part 214 the first rotation speed N1 calculated by the firstrotation speed calculation part 206, the total of the second rotationspeed N2 and the third rotation speed N3 calculated by the second andthird rotation speed calculation part 213, and the fourth rotation speedN4 which is the addition rotation speed for the fixed mode, and a finaltarget rotation speed NA of the second pump 30 is calculated by adding achange amount limit to the base value 215 by a change amount limit part216. Further, the change amount limit added by the change amount limitpart 216 is usually to converge the actual rotation speed NB withrespect to the target rotation speed NA of the second pump 30 to thetarget rotation speed NA by the change amount that can preventundershoot and overshoot (deviation to the downward value and the upwardvalue). However, when the deviation between the target rotation speed NAand the actual rotation speed NB is large, by setting a larger changeamount than this change amount, the actual rotation speed NB isconverged to the target rotation speed NA in a shorter time.

FIG. 13 is a timing chart showing changes in the target rotation speedof the second pump 30 in the servo state. This timing chart shows thechanges of each of the output pressure P1, the target rotation speed NAof the second pump 30, changes of the control mode (initial mode, F/Bmode, fixed mode), and the operational/stopped state of the second pump30 with respect to the elapsed time t. As shown in the timing chart ofthe figure, after the time point t21 when the second pump 30 operates inthe initial mode, the target rotation speed NA of the second pump 30=thefirst rotation speed N1. After that, when the initial mode transitionsto the feedback mode at the time point t22, the second rotation speed N2and the third rotation speed N3 are added to the target rotation speedNA of the second pump 30, and the target rotation speed NA=the firstrotation speed N1+the second rotation speed N2+the third rotation speedN3. Then, when the feedback mode transitions to the fixed mode at thetime point t23, the fourth rotation speed N4 is further added to thetarget rotation speed NA of the second pump 30, and the target rotationspeed NA=the first rotation speed N1+the second rotation speed N2+thethird rotation speed N3+the fourth rotation speed N4.

As described above, in the hydraulic control device of the embodiment,the target rotation speed of the second pump 30 in the initial mode isthe first rotation speed N1 alone, and the reason for this will bedescribed. In FIG. 14, (a) is a timing chart showing changes in eachvalue when the target rotation speed of the second pump 30 in theinitial mode is the first rotation speed N1+the second rotation speedN2, and (b) is a timing chart showing changes in each value when thetarget rotation speed in the initial mode is the first rotation speed N1alone. The timing charts in the figure show the changes of each of thechanges in the control mode (initial mode, F/B mode, fixed mode), thetarget rotation speed NA and the actual rotation speed NB of the secondpump 30, the line pressure PH (estimated value), the output pressure P1,and the low hydraulic pressure P3 (estimated value) with respect to theelapsed time t. In the hydraulic control device of the embodiment, asshown in (b) of the figure, the target rotation speed NA of the secondpump 30 in the initial mode is the first rotation speed N1 alone, andthe target rotation speed NA in the feedback mode following the initialmode is the first rotation speed N1+the second rotation speed N2+thethird rotation speed N3, and a condition for transitioning from theinitial mode to the feedback mode is that it is determined that theoutput pressure P1 matches the estimated value of the line pressure PHas described later. On the other hand, as shown in (a) of the figure, ifthe target rotation speed NA in the initial mode is the first rotationspeed N1+the second rotation speed N2, due to the addition of the secondrotation speed N2 in the initial mode, the output pressure P1 starts todecrease during the initial mode (before transitioning to the feedbackmode) and becomes a value close to the low hydraulic pressure P3. As aresult, it is determined that the feedback mode ends immediately afterthe transition to the feedback mode, and the mode transitions to thefixed mode, whereby a phenomenon occurs in which the fourth rotationspeed N4, which is a fixed mode addition term, is added before the thirdrotation speed N3, which is the feedback addition amount, is added.Therefore, the transition from the initial mode to the feedback modecannot be stably determined, and as a result, there is a problem thatthe time required for the feedback mode to actually end becomes longer,and that it takes a long time for the actual rotation speed NB of thesecond pump 30 to reach the target rotation speed NA.

In contrast, as shown in (b) of FIG. 14, when the target rotation speedNA in the initial mode is the first rotation speed N1 alone and thetarget rotation speed NA in the feedback mode following the initial modeis the first rotation speed N1+the second rotation speed N2+the thirdrotation speed N3, then the output pressure P1 does not decrease duringthe initial mode, and the state of matching the line pressure PH ismaintained. As a result, there is no longer a possibility that it isdetermined that the feedback mode ends immediately after the transitionto the feedback mode, so the transition from the initial mode to thefeedback mode can be stably determined, and the time required toactually end the feedback mode can be kept short. Therefore, it ispossible to shorten the time required for the actual rotation speed NBof the second pump 30 to reach the target rotation speed NA.

Here, the details of the control in the feedback mode will be described.FIG. 15 is a timing chart showing changes in each value in the feedbackmode. The timing chart in the figure shows the changes of each of thechanges in the control mode (initial mode, F/B mode, fixed mode), thefeedback amount (the feedback amount of the target rotation speed NA ofthe second pump 30), the target rotation speed NA and the actualrotation speed NB of the second pump 30, the value DN of the differencebetween the target rotation speed NA and the actual rotation speed NB,the output pressure P1 (sensor value), the line PH (estimated value),and the low hydraulic pressure P3 (estimated value) and the lowhydraulic pressure P3 (estimated value) with respect to the elapsed timet.

Here, in the initial mode before the time point t31, the operation stateof the second pump 30 transitions from the initial mode to the feedbackmode when the feedback mode transition condition described later issatisfied. Prior to the time point t31, the target rotation speed NA ofthe second pump 30 is NA=the first rotation speed N1. Then, when theoperation state of the second pump 30 is set to the feedback mode at thetime point t31, the second rotation speed N2 and the third rotationspeed N3 are then added to the target rotation speed NA of the secondpump 30. Then, during the feedback mode from the time point t31 to thetime point t34, the time region (update region) in which the feedbackamount is updated is between the time point t31 and the time point t32,and in the update region, the target rotation speed NA graduallyincreases as the feedback amount is updated. Then, when the actualrotation speed NB exceeds a predetermined range L1 (falling outside therange) with respect to the target rotation speed NA at the time pointt32, the update of the feedback amount is stopped, and thereafter, itbecomes a hold region where the update of the feedback amount istemporarily stopped until the time point t33. In the hold region, sincethe update of the feedback amount is stopped, the target rotation speedNA becomes constant. Further, since the actual rotation speed NB is fedback to the target rotation speed (instructed rotation speed) NA by thefeedback control inside the driver 34 for the second pump 30, even inthe hold region, the actual rotation speed NB of the second pump 30follows the target rotation speed NA.

After that, when the actual rotation speed NB falls within thepredetermined range L1 with respect to the target rotation speed NA atthe time point t33, the hold region transitions to the update regionagain, and the update of the feedback amount is restarted. Here, therange L1 having a predetermined value range is set on the high rotationspeed side and the low rotation speed side with respect to the targetrotation speed NA, and the update region and the hold region areswitched depending on whether the actual rotation speed NB is withinthat range. Alternatively, as shown in the changes in the value DN ofthe difference between the target rotation speed NA and the actualrotation speed NB shown in FIG. 15, it is also the same by determiningwhether the value DN of the difference is within a predetermined rangeL2.

After that, when the fixed mode transition condition described later issatisfied at the time point t34, the operation state of the second pump30 transitions from the feedback mode to the fixed mode. Therefore,after the time point t34, the target rotation speed NA and the feedbackamount of the second pump 30 are fixed (constant) in the fixed mode. Inthe fixed mode, the target rotation speed NA of the second pump 30 isNA=the first rotation speed N1+the second rotation speed N2+the thirdrotation speed N3+the fourth rotation speed N4.

In this way, in the feedback mode, time regions for performing thefeedback control include the update region in which the feedback amountof the target rotation speed NA is updated and the hold region in whichthe update of the feedback amount of the target rotation speed NA istemporarily stopped. Further, switching from the update region in whichthe feedback amount is updated to the hold region in which the update ofthe feedback amount is temporarily stopped is performed based on thatthe actual rotation speed NB of the second pump 30 with respect to thetarget rotation speed NA of the second pump 30 has become outside thepredetermined range L1.

Here, the feedback mode transition condition for transitioning from theinitial mode to the feedback mode will be described. The feedback modetransition condition is a condition that it is determined that theoutput pressure P1 matches the estimated value of the line pressure PHin the initial mode. The reason for this is as follows. That is, whenthe second pump 30 transitions from the stopped state to the initialmode, since the control start mode of the second pump 30 is set, anovershoot occurs in which the actual rotation speed NB of the secondpump 30 deviates significantly upward from the target rotation speed NA,as shown by the reference numeral Y in FIG. 15. As a result, the bypassvalve 58 may close and a differential pressure may be generated betweenthe line pressure PH and the output pressure P1 depending on thevariation and the like of the solid product. When the mode transitionsto the feedback mode as it is when such a phenomenon occurs, the controlamount (feedback amount) in the feedback mode may not be calculatedcorrectly. Therefore, here, the feedback mode transition condition is acondition that it is determined that the output pressure P1 matches theestimated value of the line pressure PH in the initial mode.

FIG. 16 is a graph for illustrating determination of matching betweenthe output pressure P1 and the estimated value of the line pressure PH.The graph in the figure shows the changes of each of the operation state(stopped/operational) of the second pump 30, the changes in the controlmode (initial mode and F/B mode), the target rotation speed NA and theactual rotation speed NB of the second pump 30, the output pressure P1,the line pressure PH (estimated value), and the differential pressurebetween the line pressure PH (estimated value) and the output pressureP1 (ΔP=|line pressure (estimated value)−output pressure P1|) withrespect to the elapsed time t.

Here, the target rotation speed NA of the second pump 30 becomes thefirst rotation speed N1 at the time point t41 in the initial mode. As aresult, the actual rotation speed NB of the second pump 30 also startsto increase. Further, at the time point t41, a first timer (feedbackforced transition timer) TM21 starts the countdown. The first timer TM21is a backup timer for preventing a case of being unable to transition tothe feedback mode when countdown completion conditions of a second timerTM22 and a third timer TM23 (to be described later) are not satisfied.After that, when the difference between the target rotation speed NA andthe actual rotation speed NB of the second pump 30 becomes less than orequal to a predetermined value at the time point t42, the second timerTM22 starts the countdown. After that, the differential pressure ΔPbetween the line pressure PH (estimated value) and the output pressureP1 exceeds a predetermined threshold value D1 at the time point t43, andthe differential pressure ΔP falls below the threshold value D1 at thetime point t44. As a result, the third timer (confirmation timer) TM23starts the countdown. The third timer TM23 is reset when thedifferential pressure ΔP exceeds the threshold value D1. When both thesecond timer TM22 and the third timer TM23 complete the countdown, it isdetermined that the output pressure P1 and the estimated value of theline pressure PH match, and the mode transitions to the feedback mode.Even if both the second timer TM22 and the third timer TM23 do notcomplete the countdown, when the first timer TM21 completes thecountdown, the feedback mode is forcibly transitioned to.

Next, the fixed mode transition condition for transitioning from thefeedback mode to the fixed mode will be described. For a fixed modetransition condition, in a state where the difference between the outputpressure P1 and the estimated value of the low hydraulic pressure P3 isequal to or less than a predetermined value PM (P1−P3 (estimatedvalue)<PM), and the change amount of the difference between the outputpressure P1 and the estimated value of the low hydraulic pressure P3 isgreater than or equal to a first predetermined value DP1 and less thanor equal to a second predetermined value DP2 (DP1<A (P1−P3 (estimatedvalue))<DP2), the mode transitions to the fixed mode when apredetermined time has elapsed. Therefore, when the timer (fixed modeforced transition timer) TM11 (see FIG. 15) for measuring the time inthe state where the change amount of the difference between the outputpressure P1 and the estimated value of the low hydraulic pressure P3 isgreater than or equal to the predetermined value DP1 and less than orequal to the predetermined value DP2 (DP1<A (P1−P3 (estimatedvalue))<DP2) completes the countdown, the mode transitions to the fixedmode. Further, if the above conditions are not satisfied during thecountdown of the timer TM11, the timer TM11 is reset.

The reason why the fixed mode forced transition timer TM11 is requiredunder the above fixed mode transition condition is as follows. That is,when the feedback state is continued, the feedback amount iscontinuously updated, whereby the target rotation speed NA may continueto increase and the fuel efficiency of the vehicle may deteriorate.Then, since the degree of deterioration of fuel efficiency is largercompared with a case where the feedback amount is fixed, the fixed modeforced transition timer TM11 is used to transition to the fixed mode.

Next, the change of each value in the initial mode, the feedback mode,and the fixed mode will be described. FIG. 17 is a timing chart showingchanges of each value in each mode. The timing chart shows the changesof each of the servo execution determination flag(execution/non-execution), the target rotation speed NA and the actualrotation speed NB of the second pump 30, the feedback mode transitiondetermination timer TM22, the output pressure P1, the low hydraulicpressure P3 (estimated value), the output pressure P1−the low hydraulicpressure P3 (estimated value), the servo state stabilization counter,and the feedback correction amount (P term, I term, F/B term) withrespect to the elapsed time t.

In the timing chart of FIG. 17, in the initial mode before the timepoint t53, the target rotation speed NA of the second pump 30 increasesby changing the servo execution determination flag from 0(non-execution) to 1 (execution) at the time point t51. After that, theactual rotation speed NB of the second pump 30 increases following thetarget rotation speed NA. As a result, the output pressure P1 graduallydecreases. When the difference between the actual rotation speed NB andthe target rotation speed NA becomes less than or equal to apredetermined value at the time point t52 (reference numeral A), thefeedback mode transition determination timer TM22 starts the countdown.After that, the feedback mode transition determination timer TM22completes the countdown at the time point t53 (reference numeral B), andthe output pressure P1−the low hydraulic pressure P3 (estimated value)becomes less than or equal to a predetermined value P1 (referencenumeral C), whereby the mode transitions from the initial mode to thefeedback mode. As a result, thereafter, the rotation speed (thirdrotation speed N3) corresponding to a correction amount M for thefeedback control is added to the target rotation speed of the secondpump 30. The correction amount M for the feedback control here is avalue corresponding to the F/B term, which is the sum (P term+I term) ofthe P term (proportional term) and the I term (integral term).

After that, when it is determined that the change amount of the outputpressure P1−the low hydraulic pressure P3 (estimated value) between thetime point t54 and the time point t55 in the feedback mode is within apredetermined range (reference numeral D), the mode transitions to thefixed mode at the time point t55. That is, here, the servo statestabilization counter completes the countdown when the change amount ofthe output pressure P1−the low hydraulic pressure P3 (estimated value)is within the predetermined range to transition to the fixed mode. Inthe fixed mode after the time point t55, the target rotation speed NA ofthe second pump 30 becomes constant. Then, when the servo executiondetermination flag becomes 0 (non-execution) at the time point t56, thesecond pump 30 stops and the fixed mode ends.

FIG. 18 is a flowchart showing transition conditions of the initialmode, the feedback mode, and the fixed mode, and is a flow showing theflow of processing corresponding to the timing chart of FIG. 17. Here,first, it is determined whether the servo is operating (servo executiondetermination flag is 1 (execution)) (step ST1-1), and as a result, whenthe servo is not operating (NO), the timer (feedback mode transitiondetermination timer) TM22 is set (step ST1-2) to set the initial mode(step ST1-3). On the other hand, when the servo is operating in stepST1-1 (YES), then it is determined whether the deviation between thetarget rotation speed NA and the actual rotation speed NB of the secondpump 30 is less than or equal to a predetermined value, or whether it isa mode other than the initial mode (step ST1-4). As a result, when thedeviation between the target rotation speed NA and the actual rotationspeed NB of the second pump 30 is not less than or equal to thepredetermined value and is in the initial mode (NO), the timer (feedbackmode transition determination timer) TM22 is set (step ST1-2) to set theinitial mode (step ST1-3). On the other hand, when in step ST1-4 thedeviation between the target rotation speed NA and the actual rotationspeed NB of the second pump 30 is less than or equal to thepredetermined value or the mode is other than the initial mode (YES),then it is determined whether the timer TM22 is less than or equal to apredetermined value (completing the countdown) (step ST1-5). As aresult, when the timer TM22 is not less than or equal to thepredetermined value (NO), the initial mode is set (step ST1-3), and whenthe timer TM22 is less than or equal to the predetermined value (YES),then it is determined whether the output pressure P1−the low hydraulicpressure P3 (estimated value) is less than or equal to a predeterminedvalue (step ST1-6). As a result, when the output pressure P1−the lowhydraulic pressure P3 (estimated value) is not less than or equal to thepredetermined value (NO), the feedback term is calculated (step ST1-7),and the mode transitions to the feedback mode (F/B mode) (step ST1-8).On the other hand, when in step ST1-6 the output pressure P1−the lowhydraulic pressure P3 (estimated value) is less than or equal to thepredetermined value (YES), then it is determined whether the changeamount of the output pressure P1−the low hydraulic pressure P3(estimated value) is less than or equal to the predetermined value andwhether a predetermined time has elapsed (step ST1-9). As a result, whenthe change amount of the output pressure P1−the low hydraulic pressureP3 (estimated value) is not less than or equal to the predeterminedvalue or when the predetermined time has not elapsed (NO), the feedbackterm is calculated (step ST1-7), and the mode transitions to thefeedback mode (step ST1-8). On the other hand, when in step ST1-9 thechange amount of the output pressure P1−the low hydraulic pressure P3(estimated value) is less than or equal to the predetermined value andthe predetermined time has elapsed (YES), the mode transitions to thefixed mode (step ST1-10).

Here, in the flowchart of FIG. 18, when the deviation between the targetrotation speed NA and the actual rotation speed NB of the second pump 30is less than or equal to the predetermined value in step ST1-4 (YES), itcorresponds to the reference numeral A in the timing chart of FIG. 17;when the timer is less than or equal to the predetermined value in stepST1-5 (YES), it corresponds to the reference numeral B; when the outputpressure P1−the low hydraulic pressure P3 (estimated value) is less thanor equal to the predetermined value in step ST1-6 (YES), it correspondsto the reference numeral C; and when the change amount of the outputpressure P1−the low hydraulic pressure P3 (estimated value) is less thanor equal to the predetermined value and the predetermined time haselapsed in step ST1-9 (YES), it corresponds to the reference numeral D.

As described above, according to the hydraulic control device of theembodiment, in the calculation of the feedback amount with respect tothe target rotation speed NA of the second pump 30, time regions forperforming calculation of the feedback amount include the update regionin which the feedback amount of the target rotation speed NA is updatedand the hold region in which the update of the feedback amount of thetarget rotation speed NA is temporarily stopped. As a result, comparedwith a case where the update of the feedback amount is continuouslyupdated without being temporarily stopped, since an excessive increasein the rotation speed of the second pump 30, which is an electric pump,can be suppressed, the discharge pressure of the second pump 30 can bestabilized. Therefore, since the operation of the hydraulic operationpart can be stabilized, the effect of reducing the fuel consumption ofthe vehicle can be obtained more reliably.

Further, in the hydraulic control device of the embodiment, the updateregion is switched to the hold region when the actual rotation speed NBof the second pump 30 with respect to the target rotation speed NA ofthe second pump 30 falls outside the predetermined range, whereby theactual rotation speed NB can be prevented from becoming a value thatdeviates significantly from the target rotation speed NA, and theaccuracy of the actual rotation speed NB with respect to the targetrotation speed NA can be improved.

Further, since the hold region is switched to the update region when theactual rotation speed NB of the second pump 30 with respect to thetarget rotation speed NA of the second pump 30 returns to thepredetermined range, the update of the feedback amount is restarted whenthe actual rotation speed NB is close to the target rotation speed NA,whereby the actual rotation speed NB can be transitioned to the finaltarget rotation speed NA earlier.

Further, in the hydraulic control device of the embodiment, the feedbackcontrol is ended and the mode transitions to the fixed mode in which thetarget rotation speed NA of the second pump 30 is constant on thecondition that the predetermined time has elapsed since the differencebetween the output pressure P1 (which is the pressure value of the firstoil) and the estimated value of the low hydraulic pressure P3 (which isthe pressure value of the third oil) becomes less than or equal to thepredetermined value and that the difference between the output pressureP1 and the estimated value of the low hydraulic pressure P3 perpredetermined time has become within the predetermined range.

If the feedback control is continued, since the feedback amount iscontinuously updated, the target rotation speed NA of the second pump 30continues to increase, and the fuel efficiency of the vehicle maydeteriorate. Then, the degree of deterioration of fuel efficiency islarger compared with a case where the feedback amount is fixed.Therefore, here, the feedback mode is transitioned to the fixed modeaccording to the above conditions.

Although the embodiments of the disclosure have been described above,the disclosure is not limited to the above embodiments, and variousmodifications may be made within the scope of claims and the technicalideas described in the specification and drawings.

What is claimed is:
 1. A hydraulic control device in which a second pumpand a bypass valve that are driven by a motor are connected in parallelbetween a first pump and a hydraulic operation part of a transmission,and which is switchable between a first state of supplying a first oilfrom the first pump to the hydraulic operation part via the bypass valveand a second state of pressurizing with the second pump the first oilsupplied from the first pump and supplying the pressurized first oil asa second oil to the hydraulic operation part, the hydraulic controldevice comprising: a hydraulic pressure detection part which detects anoil pressure of the first oil on a suction side in the second pump; anda control part which calculates a target rotation speed of the secondpump in the second state, wherein the control part uses a pressure valueof the first oil detected by the hydraulic pressure detection part, anestimated value of a pressure value of oil supplied to the hydraulicoperation part, and an estimated value of a pressure value of a thirdoil supplied from the first pump to another hydraulic operation part ora lubrication target operating at a lower pressure than the hydraulicoperation part in the transmission to calculate the target rotationspeed of the second pump for matching the pressure value of the firstoil with the estimated value of the pressure value of the third oil, andsubtracts the estimated value of the pressure value of the third oilfrom the pressure value of the first oil detected by the hydraulicpressure detection part to calculate a feedback amount with respect tothe target rotation speed, wherein time regions for performingcalculation of the feedback amount comprise: an update region in whichthe feedback amount with respect to the target rotation speed isupdated; and a hold region in which update of the feedback amount withrespect to the target rotation speed is temporarily stopped.
 2. Thehydraulic control device according to claim 1, wherein switching fromthe update region to the hold region is performed based on that anactual rotation speed of the second pump with respect to the targetrotation speed of the second pump has become outside a predeterminedrange.
 3. The hydraulic control device according to claim 2, whereinswitching from the hold region to the update region is performed basedon that the actual rotation speed of the second pump with respect to thetarget rotation speed of the second pump has changed from being outsidethe predetermined range to being within the predetermined range.
 4. Thehydraulic control device according to claim 1, wherein the control partends a feedback control and transitions to a control which keeps thetarget rotation speed constant on a condition that a predetermined timehas elapsed since a difference between the pressure value of the firstoil and the estimated value of the pressure value of the third oilbecomes less than or equal to a predetermined value and that thedifference between the pressure value of the first oil and the estimatedvalue of the pressure value of the third oil per predetermined time hasbecome within a predetermined range.
 5. The hydraulic control deviceaccording to claim 2, wherein the control part ends a feedback controland transitions to a control which keeps the target rotation speedconstant on a condition that a predetermined time has elapsed since adifference between the pressure value of the first oil and the estimatedvalue of the pressure value of the third oil becomes less than or equalto a predetermined value and that the difference between the pressurevalue of the first oil and the estimated value of the pressure value ofthe third oil per predetermined time has become within a predeterminedrange.
 6. The hydraulic control device according to claim 3, wherein thecontrol part ends a feedback control and transitions to a control whichkeeps the target rotation speed constant on a condition that apredetermined time has elapsed since a difference between the pressurevalue of the first oil and the estimated value of the pressure value ofthe third oil becomes less than or equal to a predetermined value andthat the difference between the pressure value of the first oil and theestimated value of the pressure value of the third oil per predeterminedtime has become within a predetermined range.